Power management

Power management forum

LM2576S-ADJEVM: LM2576-ADJ

Marcelo Manoel de Oliveira

Prodigy 30 points

Part Number: LM2576S-ADJEVM
Other Parts Discussed in Thread: LM2576

Hi There !!!

I´ve got problem relating LM2576-ADJ, some parts of the batch, do not work well regulating and converting the output voltage and we´ve noitced also the frequency is out of range (oscillating around 25kHz) where the correct work frequency is about 52kHz.

But some parts work perfectly on our application !!!

Could you help us identify the occurence of the effect?

Follow below the parts of the batch which we´ve got problem:

JM34RP

Parts of the batch it works well:

JM61RP, JM33RP, JM54RP

over 7 years ago

0 Frank De Stasi over 7 years ago

TI__Guru 70235 points

Please share you schematic, input, output and load values, and a snapshot of the layout.

0 Marcelo Manoel de Oliveira over 7 years ago in reply to Frank De Stasi

Prodigy 30 points

J2 is a Potentiometer for the LM2576 regulation adjustment from Vref til 5V.

0 Marcelo Manoel de Oliveira over 7 years ago in reply to Marcelo Manoel de Oliveira

Prodigy 30 points

Hello, thank you for the prompt reply.

J2 is a potentiometer for the LM2576 regulation adjustment of the output voltage from 1,25V (vref) to 5V.

Best regards.

0 Frank De Stasi over 7 years ago in reply to Marcelo Manoel de Oliveira

TI__Guru 70235 points

I do not see an output capacitor directly connected to the output of the inductor.

This may be a misprint on the schematic, but a cap is required at that point.

Also, using a variable resistor connectect to the FB node is a bad idea.

The FB input is very sensitive and can easily pick up noise that can disrupt the opereation

of the regulator.

I am not sure what kind of load you are showing; it might help to explain.

Also, if you can supply a snapshot of you layout we can look at that as well.

If you believe that the units are defective, please return them to TI for evaluation.